This invention relates to a built-in or added mechanical means referred to as a stop, such as a solid structure built-in, protruding or extending continuously from either the top, herein referred to as bonnet, or the bottom plate, herein referred to as valve body, of a conventional diaphragm-sealed valve or a separate solid structure placed between the bonnet and the valve body during the assembly of a diaphragm-sealed valve. The stop or stops protect a flexible diaphragm placed between the bonnet and the valve body of a valve from distortion caused by applying a greater than requisite compression on the periphery of the flexible diaphragm which is synonymous to controlling the installed thickness of the periphery of the diaphragm during assembly.
Diaphragm-sealed valves are used in different industries for controlling the feeding and/or transporting of liquids from one point to another. Diaphragm-sealed valve and valve are used interchangeably herein and refer to the same. Existing diaphragm-sealed valves comes in different designs and construction. However, the main parts making up a diaphragm valve are a bonnet, a valve body, a diaphragm between the bonnet and valve body, a compressor connected to a stem and/or handle to control the amount of pressure applied to the center portion of the weir diaphragm and consequently to the pressure of the diaphragm upon the weir. Diaphragms are usually made of flexible material such as rubber elastomers, Buna-N, EPDM, EPDM with Teflon, silicone, Viton, etc. The bonnet and valve body are usually assembled with a fastener such as a screw that extends from the bonnet to the valve body or vice-versa. In the actual use of a diaphragm-sealed valve, after assembly the applied pressure and the release of this pressure from the flexible diaphragm upon the weir is responsible for controlling the flow of liquids through the inner surfaces of the diaphragm valve. Compression of the diaphragm upon the weir stops the flow of the liquid while the release of pressure from the diaphragm, allows the flow of the liquid.
Prior art diaphragm valves have the top plate or bonnet and bottom plate or valve body directly urging on the peripheral area of the diaphragm without having positive stops to control diaphragm thickness when the diaphragm is compressed between the top plate and the bottom plate during its assembly. Do not have positive stops, herein means that in the existing diaphragm-sealed valves, there are no parts attached or inserted directly between the top or bottom plates that can impede further movement of the top plate towards the bottom plate. Consequently, there is no means to control the pressure exerted upon the diaphragm which is located between the top and bottom plate.
In the assembly of conventional diaphragm-sealed valves prior to shipment, installation or use, a flexible diaphragm is placed between the top and bottom plate before the top and bottom plates are fastened to each other. To prevent the top plate, bottom plate and diaphragm from moving in relation to each other or shifting in position during storage and shipment, or to maintain external static seal during the initial installation of a diaphragm-sealed valve or during use, the top and bottom plates are pressed on the diaphragm by the fasteners used to connect the top and bottom plates. External seal or external static seal means preventing fluid leakage to the surrounding environment. With this conventional design, the amount of pressure applied on the plates during the assembly of the diaphragm-sealed valve is necessarily variable because there is no means to control or determine the pressure applied on the diaphragm because the diaphragm is flexible and easily gives in to the applied pressure. The thickness of a compressed diaphragm is indicative of the amount of pressure applied. A thin bulging diaphragm usually indicates excessive applied pressure. Excessive pressure on the diaphragm can damage the diaphragm even before use, it can cut, deform or damage the diaphragm which results in reduced diaphragm life, increased potential for internal leakage between valve inlet and outlet, excessive force required to effect a seal, increased potential for entrapped contaminants in damaged diaphragms, and reduced flow capacity due to diaphragm deformation.
It is therefore an object of this invention to provide a means for restricting the amount of pressure applied to the diaphragm during the assembly of the diaphragm-sealed valve to prevent premature wear.
It is another object of this invention to provide a means for controlling the pressure applied on the diaphragm so as not to deform the diaphragm during storage, shipment and installation.